A typical size of an Internet Protocol version 4 (IPv4) packet header is 128 bytes. An IPv4 packet header includes a version field, header length field, differentiated services field, packet length field, packet identification field, flags field, fragment offset field, time-to-live field, protocol field, header checksum field, source field, and destination field. Although an IPv4 packet header can also include an options field, which may increase the size of the packet, the options field is infrequently used and, often, network devices do not support its use.